Selective soldering system

ABSTRACT

A solder machine includes a top flat carrier that holds PWBs just above a solder bath. Opposed edges of the carrier are coupled to a frame and each edge can be independently raised or lowered by a respective piston. Also, the base of the frame can pivot along one of its edges to provide a second degree of freedom of motion to the top flat carrier in dipping the PWBs relative to the solder bath, thereby providing a solder machine with a relatively small footprint that nonetheless can achieve precise soldering of PWBs.

FIELD OF THE INVENTION

The present invention relates generally to printed wiring board (PWB)soldering machines that dip, in two degrees of freedom, PWBs into asolder bath to effect soldering.

BACKGROUND OF THE INVENTION

Solder machines are used to dip components such as printed wiring boardsinto solder baths to effect mechanical-electrical connections. Toundertake this dipping automatically, previous wave soldering systemshave been used that have been relatively bulky to accommodate necessaryconveyance of the PWBs into the solder bath at the desired locations ofthe PWBs. Furthermore, the bulkiness of the prior wave solderingmachines has been necessitated to accommodate required solderingprecision. Such prior machines have typically consumed around threesquare meters of valuable factory floor space.

SUMMARY OF THE INVENTION

A selective soldering machine provides greater soldering precision witha smaller footprint (around a single square meter) by means of using twodegrees of freedom of the component that dips the PWB into the solderbath.

Accordingly, a selective soldering machine has a solder bath, preferablycoated with ceramic, and a frame juxtaposed with the solder bath andincluding a carrier configured for holding a component such as a PWB tobe soldered. The frame moves the carrier in first and second degrees offreedom relative in order to the solder bath to solder the componentonly on needed areas by, e.g., using nozzles for applying melted solderto the areas.

The first degree of freedom can be provided by tilting a first edge ofthe carrier using a linear actuator, e.g., a first piston, coupled tothe first edge. A second linear actuator such as a second piston may becoupled to a second edge of the carrier and operable independently ofthe first piston. The first and second edges are opposed to each other.The frame can also include a base below the carrier and coupled thereto,with the frame being pivotable by, e.g., a base piston to provide thesecond degree of motion.

In another aspect, a method of soldering a printed wiring board (PWB)includes pivoting, relative to a solder bath, a top flat carrier holdingthe PWB, and pivoting, relative to the solder bath, a base of a frameconnected to the top flat carrier. Pivoting of the top flat carrier iscoordinated with pivoting of the base to effect soldering of at leastone preselected part of the PWB using solder in the solder bath.

In still another aspect, a solder machine includes a top flat carrierconfigured to hold at least one and preferably plural printed wiringboards (PWB) and a solder bath disposed beneath the flat carrier. Firstand second pistons are coupled to a frame and to respective opposedfirst and second edges of the carrier and are independently operable toraise or lower the respective edges. A base of the frame is disposedbelow the top flat carrier. The base is pivotable along an edge thereofto provide a degree of freedom of motion to the top flat carrier indipping the PWB relative to the solder bath.

The details of the present invention, both as to its structure andoperation, can best be understood in reference to the accompanyingdrawings, in which like reference numerals refer to like parts, and inwhich:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the present solder machine, showing PWBson the top carrier;

FIG. 2 is a perspective view of the present solder machine with the PWBsand operator display removed for clarity;

FIG. 3 is a perspective view of the frame and top carrier with thehousing of the machine removed; and

FIG. 4 is a perspective view of the frame and top carrier illustratingthe two degrees of freedom of motion of the top carrier.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Terms of height such as “top”, “bottom”, “above”, “below”, “upper”,“lower”, “higher”, “lower”, etc. as used herein are relative to thesoldering machine when it is positioned on the floor of an assemblyplant as intended.

Referring initially to FIGS. 1 and 2, a solder machine is shown,generally designated 10, which includes a shroud or housing 12 enclosinga frame 14 that is coupled to a solder bath 16 holding solder fordip-soldering components such as printed wiring boards (PWB) 18. Thesolder machine 10 may support a processor 20 (shown schematically inFIG. 1) that controls motion of the frame in accordance with disclosurebelow. The processor 20 may output information on a computer monitor 22if desired.

Details of the frame 14 and how it moves with two degrees of freedomrelative to the (non-moving) solder bath 16 can be seen incross-reference to FIGS. 3 and 4. The frame 14 includes a top flatgenerally rectilinear PWB carrier 24 which includes support structure 26for supporting one or more PWBs. The PWBs may plug into the supportstructure 26 or may rest on it or be clamped or otherwise held by thesupport structure 26. It is to be appreciated that parts of the PWBs tobe soldered extend below a central cavity 28 defined by the carrier 24and toward the solder bath below, so that as the carrier 24 is moved inaccordance with disclosure below the portions of the PWBs are dippedinto molten solder.

As shown, the frame 24 includes two vertical legs 30 that support thecarrier 24 in the generally horizontal orientation shown. Specifically,each leg 30 includes a respective vertically-oriented edge piston 32that is coupled to a respective edge of the carrier 24, with opposededges of the carrier 24 thus being coupled to respective edge pistons 32as best shown in FIG. 4. The edge pistons 32 are independently operableto raise and lower their respective edges of the carrier 24 to therebytilt the carrier 24 in what can be regarded as a Cartesian x-dimensionas shown by the arrow 33.

In turn, the legs 30 are supported on a base 34 of the frame 14. As bestshown in FIG. 4, the base 34 includes a U-shaped pivot bar 36 theopposed arms of which are hingedly coupled at their free ends tostationary horizontal base supports 38. A base piston 40 is coupled tothe pivot bar 36 to pivot it up and down relative to the base supports38 as shown by the arrow 42. This motion, since the pivot axis is at theends of the U-shaped pivot bar 36 and, hence, is off-center relative tothe carrier 24, tilts the carrier 24 in a dimension that is orthogonalto the x-dimension, and that consequently may be thought of as theCartesian y-dimension.

Put another way, the edge pistons 32 tilt the carrier 24 about a line 44(FIG. 4) that is parallel to the edges to which the edge pistons 32 arecoupled, whereas the base piston 40 tilts the carrier 24 about a line 46that is perpendicular to the edges of the carrier 24 to which the edgepistons are coupled.

Accordingly, one degree of freedom is provided by the pivoting of thetop carrier 24 by the two edge pistons 32 coupled to opposed edges ofthe carrier 24 that can independently move their respective edge up anddown. The bottom of the frame 14, and more specifically the pivot bar36, which is distanced from the top carrier 24, pivots along one of itsedges (i.e., the free ends of the arms of the U-shaped pivot bar 36)owing to the base piston 40, to provide the other degree of freedom.

Each piston 32, 40 is electrically actuated by a respectiveelectrically-controlled actuator such as a servo that is controlled bythe processor 20 as desired to tilt the carrier 24 to solderpredetermined parts of the PWBs 18. Thus, pivoting motion of the carrier24 is coordinated with pivoting motion of the pivot bar 36 to dipselected parts of the PWBs relative to the solder bath 16, which isenclosed by the frame 14 just beneath the carrier 24, with the solderbath remaining stationary as the carrier 24 moves. In this way, onlyneeded areas of the PWB are soldered by, e.g., using nozzles forapplying melted solder from the bath to the areas.

While the particular SELECTIVE SOLDERING SYSTEM is herein shown anddescribed in detail, it is to be understood that the subject matterwhich is encompassed by the present invention is limited only by theclaims. For example, pistons may be used but other linear actuators suchas rack-and-pinion style actuators driven by, e.g., stepper motors maybe used.

1-12. (canceled)
 13. A solder machine, comprising: a top flat carrierconfigured to hold at least one printed wiring board (PWB); at least onesolder bath disposed beneath the flat carrier; first and second linearactuators coupled to a frame and to respective opposed first and secondedges of the carrier, the linear actuators being independently operableto raise or lower the respective edges; and a base of the frame anddisposed below the top flat carrier, the base being pivotable along anedge thereof to tilt and thereby provide a degree of freedom of motionto the top flat carrier in dipping the PWB relative to the solder bath,the base including a pivot element, a base actuator being coupled to thepivot element to pivot the pivot element up and down, a base pivot axisbeing defined at ends of the pivot element and hence being off-centerrelative to the carrier such that moving the base actuator tilts thecarrier.
 14. The solder machine of claim 13, wherein the first andsecond edges are opposed to each other.
 15. (canceled)